C *32 3 



D. SILICEOUS. 



a. Earth]/ Quartz; ftru£ture loofe as that of 

 mofs, which it refembles; exceedingly brittle, 

 and light as pumice; colour white, greyifh, and 

 dark. 



b. Ferruginous Quartz; hard, fra&ure fplin- 

 tery colour brown, or brownifh purple ; fome- 

 times fchiftofe, fometimes of the texture of mofs. 



c. Earthy Quartz with Actinolite ; greenifh grey 

 colour, with yellowifh green lumps, and fpecks 

 and blotches of red; fraclure fplintery and un- 

 even. 



d. Rarthy Hornstone, refembles earthy quartz, 

 but of a finer and clofer grain ; colour reddifh 

 grey mixed with green, brownifh or blackifh ; 

 ftructure thick flaty ; fra&ure fplintery. 



e. Ferruginous Horns tone ; hard and clofe 

 grained, colour reddifh brown ; gives a pale red 

 ftreak. 



f. Siliceous Schistus with Limestone ; of a dark 

 yellowifh grey colour ; frafture fplintery ; the 

 grain very fine and clofe. 



g. Siliceous Schistus ivith Argillite ; colour 

 light bluifh grey or purplifh grey ; frafture fine 

 fplintery ; in the grofs, flaty. 



h. Siliceous 



